1. Technical Field
The disclosure relates to a sensing method and device, and more particularly to a sensing method and device for sensing the position of an object.
2. Related Art
The touch devices can be classified to be resistance touch device, capacitance touch device, optical touch device, and etc according to different working principles. The merits of the optical touch device are comfortable touch feeling, low material cost, and so on.
Optical touch device has light source and sensor unit disposed at the surrounding of the touch panel or at the bottom of the device. The optical touch device operates based on the light interruption principle. That is, when the light emitted from a light source is interrupted, it means that a user is performing a touch operation, and as a result the light cannot go ahead along the original emitting direction. A sensor unit senses the light interruption and transmits a sensed signal corresponding to the light interruption to a processing unit to determine the position of the touch point.
FIG. 1 shows an optical touch device according to the related art. The touch device 10 comprises a base plate 101, a first image sensing module 103 disposed at the upper left corner of the base plate 101, a second image sensing module 104 disposed at the upper right corner of the base plate 101, a processing circuit 106 having signal connections with the first image sensing module 103 and the second image sensing module 104, and a reflection element 102 disposed at the surrounding of the base plate 101. The first and second image sensing modules are used to capture images in the touch area 107. The processing circuit 106 is used to calculate the position of an object 11 in the touch area 107 according to the captured images.
In FIG. 1, infrared ray is emitted from the image sensor modules to the object 11. The object 11 reflects the infrared ray and generates an image for determining the position of the object 11. The image received by the image sensor modules can be divided into two parts. One is the zone with higher brightness which is reflected by the reflection element 102, and the other is the dark zone because of the light interruption by the object 11.
In other words, the touch device 10 according to the related art uses the bright zone and the dark zone to provide the touch area 107, which is the area formed on the base plate 101 by the reflection element 102. In this case, when a user performs a touch operation by using the object 11 (finger or touch pen), the touch area 107 is limited in the area formed by the reflection element 102.
Because the touch device 10 according to the related art uses the bright zone generated by the reflection element 102 as references for determining the position of the object to be detected, the touch device 10 has the following shortcomings.
Firstly, the touch device is not easily to be carried with due to the size of the base plate 101 and the reflection element 102. The usage environment of the touch area is limited by the real size of the base plate 101 and the reflection element 102. Secondly, the cost of the base plate 101 and the reflection element 102 which adds additional cost of the touch device cannot be ignored. That is, the manufacture and usage of a portable electronic device comprising the related art touch device have a great limitation.
Furthermore, according to the above mentioned working principle of the optical touch device 10, reflection element 102 made of retro-reflective material must be used in the optical touch device 10, and therefore the manufacture cost of the optical touch device and the size of the reflection area of the optical touch device 10 according to the related art are limited.